Physiology of pregnancy Flashcards
What does a fertilized ovum develop into?
Blastocyst
What do the inner & outer cells of a blastocyst develop into?
Inner cells = embryo
Outer cells = placenta
When are the placenta & foetal heart functional by?
Week 5
What is the purpose of the placenta villi?
AV shunt - stops direct contact of mother & child blood
Nutrient transfer
How does foetal oxygenated blood return to the foetus?
Umbilcal vein
How does a foetus maintain a good oxygen supply?
Foetal Hb has increased ability to carry oxygen
High Hb conc in foetal blood
Bohr effect (foetal Hb can carry more oxygen in low PCO2 then high pCO2)
What is the function of hCG in pregnancy?
Prevents corpus luteum from forming
Effects development od sex organs
What are the effects of HCSinpregnancy?
Growth effects
Decreases insulin sensitivity in mother
Involved in breast development
What are the effects of progesterone in pregnancy?
Develop decidual cells
Decreases uteruscontractility
Prep for lactation
What are the effects of oestrogen in pregnancy?
Enlarges uterus
Breast developemnt
Relax ligaments
How does CRH secreted by the placenta affect the mother?
Causes increased ACTH which causes increased aldosterone & cortisol
This can lead to hypertension or oedema causing insulin resistance and gestational diabetes
What condition can HCG secreted by the placenta cause in the mother?
Hyperthyroidism
What condition can increased calcium demands from the plaenta cause in the other?
Hyperparathyroidism
How does pregnancy affect maternal cardiac output?
Increase (by 30-50%) then decreases in the last 8 weeks
How does pregnancy affect the maternal HR?
Increase (up to 90bpm)
Why does maternal blood pressure drop in the second trimester of pregnancy?
Circulation expands
Peripheral resistance decreases
What maternal haematological changes are seen in pregnancy?
PV increases (proportional with CO)
Erythropoesis increases
Decreased Hb by dilution
Iron requirement increases
What effect does progesterone have on CO2 levels?
Progesterone signals to brain to lower CO2 levels
What affect does pregnancy have on the kidneys?
Decreased GFR & renal plasma flow
Increased reabsorption of ions & water
Slight increase in urine formation
What is pre-eclampsia?
Pregnancy induced hypertension + proteinuria (<0.3g/24hrs)
What are the risk factors for pre-eclampsia?
Previous pre-eclampsia Hypertension Diabetes Renal disease Obesity Twins
When is pre-eclampsia seen?
After 20 weeks
Symptoms of pre-eclampsia
Headache Visual disturbances Papilloedema RUQ/epigastric pain Hyperreflexia
What is the first line treatment for pre-eclampsia in pregnancy?
Labetalol
How is gestational hypertension defined?
> 20 weeks
No proteinuria, no oedema
Resolves following birth
BP > 140/90
What is used to prevent & treat seizures in eclampsia?
IV Magnesium sulphate 4mg blous followed by infusion of 1g/hour
What are 2 phases of pregnancy metabolism?
<20 weeks = mothers anabolic phase
>20 weeks = increased foetal demand/starvation of the mother
How do progesterone & oestrogen affect contractility of the uterus?
Progesterone inhibits contractility
Oestrogen increases contractility
What is the role of oxytocin in labour?
Increases contractions & excitability
What controls the timing of labour?
Foetal hormones (oxytocin, adrenal gland, prostaglandin)
What are the 3 stages of labour?
1st stage = cervical dilation (8-24 hours)
2nd stage = passage through birth canal (few min-30 min)
3rd stage = expulsion of placenta
How does oestrogen affect the breasts?
Stimulates growth of ductile system
Inhibits milk production
How does progesterone affect the breast?
Development of lobule-alveolar system
Inhibits milk production
What change in hormones brings about milk production?
Drop in oestrogen & progesterone (both inhibit milk production)
Increased prolactin & oxytocin
What re the changes inprolactin in pregnancy?
Increases week 5 to birth
Stimulates colostrum
What causes the milk “let-down” reflex?
Sucking stimulus + oxytocin
